The present invention relates to a separating cyclone for at least partially separating a mixture of fluids of different density into a light fraction with a relatively low density and a heavy fraction with a relatively high density. The invention also relates to a flow body for such a separating cyclone and to a method for at least partially separating said mixture.
Known for the purpose of separating mixtures of mutually insoluble liquids, such as oil and water, are separating cyclones wherein use is made of the difference in density between water and oil to bring about the separation. The mixture for separating is set into rotation in a tube, whereby under the influence of the occurring centrifugal forces the relatively heavy water is flung against the wall of the tube and the relatively light oil moves to the centre of the tube. The oil and the water are hereby separated from each other spatially, which provides the option of discharging the oil and the water separately.
Such a separating cyclone is described in the international publication WO 89/04726. Herein a mixture of oil and water is fed axially into the cyclone and set into rotation using a number of swirl blades arranged on a flow body. Downstream of the blades the diameter of the cyclone decreases in order to increase the rotation as a result of angular momentum being sustained. In the cyclone a mixture part with a relatively large amount of light oil accumulates in a core in the centre of the cyclone, and this core is removed via an overflow outlet and a channel through the flow body in a direction opposite the direction of flow of the supplied mixture. The mixture part with a relatively large amount of the heavy water follows a path through the cyclone and is discharged further along via an underflow outlet.
A quite reasonable separating efficiency can be achieved with the known separating cyclones. The separating efficiency is however limited in that a part of the mixture flowing along the flow body and set into rotation detaches from the surface of the flow body.